This study seeks to clarify the relationship of certain respiratory variables to meditation, drowsiness, and sleep. Because (1) respiration is under voluntary and autonomic control, (2) it is tied to ARAS activity, and (3) it is a central part of meditative practices, it is felt that a study of certain respiratory parameters previously linked to ARAS activity will provide further information on the psychophysiology of meditation. Toward this aim, alveolar CO2 tension, CO2 sensitivity of the respiratory centers, ventilation, and abdominal-thoracic respiratory patterns are being measured and recorded along with psychophysiologic measures indicative of level of consciousness; ie., EEG, EMG and EOG, in meditators and in controls. This study includes three different meditative traditions, thus providing standardization of techniques for comparisons across disciplines. Analysis of data acquired thus far on meditators from all three traditions has shown interesting and significant differences between respiratory changes associated with mediation and those associated with sleep onset. Data acquired from this project could be used for further discrimination of meditation from other levels of consciousness and perhaps aid in understanding neural processes involved in gradations of attention and consciousness.